Multi-layer tube for conducting fuel in a motor vehicle

Abstract

A motor vehicle fuel conveying multi-layer co-extruded tube ( 1 ) comprising at least an innermost first layer ( 2 ) of a polyamide resin (P9T) consisting of a dicarboxylic acid component and a diamine component, wherein 60÷100% of the dicarboxylic acid component is terephthalic acid and 60÷100% of the diamine component is selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine; an intermediate second layer ( 3 ) of polyamide 6 (PA 6); an intermediate co-polyamide (CoPA)-based tie layer ( 4 ); and an external fourth layer of polyamide 12 (PA12).

1. A motor vehicle fuel conveying multi-layer tube comprising from the inside to the outside, at least:
 an innermost first layer comprising a polyamide resin (nylon 9T) consisting of a dicarboxylic acid component and a diamine component, wherein 60÷100% of the dicarboxylic component is terephthalic acid and 60÷100% of the diamine component is a diamine component selected from 1,9-nonanediamine and 2-methyl-1,8-octanediamine; 
 an intermediate second layer of polyamide 6 (PA6) comprising an impact modified polyamide 6; 
 a third layer consisting of a co-polyamide (CoPa)-based tie layer and an external fourth layer of polyamide 12 (PA12). 
 
     
     
       2. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said polyamide 6 has a melting point comprised between 210 and 230° C., a tensile strength at yield comprised between 25 and 35 MPa, a tensile elongation at break greater than 150% and an Izod impact strength (notched; 23° C.) between 100 and 200 J/m. 
     
     
       3. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said third layer is a tie layer consisting of a PA6/PA12 co-polyamide. 
     
     
       4. The motor vehicle fuel conveying multi-layer tube according to  claim 3 , wherein said PA6/PA12 co-polyamide has a inching point comprised between 190 and 210° C., a tensile strength comprised between 90 and 110 MPa, and a tensile modulus comprised between 550 and 750 MPa. 
     
     
       5. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said fourth layer comprises an impact- and thermal-resistance-modified polyamide 12. 
     
     
       6. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said polyamide 12 has a melting point comprised between 170 and 180° C., a tensile strength at yield comprised between 25 and 35 MPa, flexural strength comprised between 20 and 30 MPa, flexural modulus comprised between 400 and 600 MPa, an impact strength (Charpy, notched) comprised between 100 and 120 kJ/m 2  at. 23° C. and between 10 and 20 kJ/m 2  at −40° C. 
     
     
       7. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said first layer has a thickness in the range 0.10 mm÷0.25 mm. 
     
     
       8. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said second layer has a thickness in the range 0.20 mm÷0.30 mm. 
     
     
       9. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said third layer has a thickness in the range 0.10 mm÷0.30 mm. 
     
     
       10. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said fourth layer has a thickness in the range 0.35 mm÷0.55 mm. 
     
     
       11. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said first, second, third and fourth layer are co-extruded. 
     
     
       12. The motor vehicle fuel conveying multi-layer tube according to  claim 1 , wherein said multi-layer tube further comprises a fifth layer external to said fourth layer, said fifth layer being of a material consisting of a mixture of a polyamide and a functionalized polyolefin, wherein the polyamide of the mixture is a matrix of the mixture of a polyamide and a functionalized polyolefin, the mixture comprising nanofillers. 
     
     
       13. The motor vehicle fuel conveying multi-layer tube according to  claim 12 , wherein said material has a melting point comprised between 200 and 220° C. and a flexibility comprised between 25 and 50 Shore D, said material further demonstrating creep resistance up to approximately 200° C. 
     
     
       14. The motor vehicle fuel conveying multi-layer tube according to  claim 13 , wherein said first, second, third, fourth and fifth layer are co-extruded.